In Long Term Evolution Release 11 (LTE R11), a concept of Channel State Information (CSI) process is introduced to provide a support to Coordinated Multipoint Transmission and Reception (COMP): each CSI process corresponds to a Channel State Information Reference Signal (CSI-RS) resource and a Channel State Information-Interference Measurement Resource (CSI-IMR), wherein a Transmission Mode (TM) supporting COMP is TM10.
Wherein, a CSI-RS resource is defined in TS 36.211-b30, and when a system supports at most 8 antenna ports, a CSI-RS is transmitted on antenna ports p=15, p=15, 16, p=15, . . . , 18 and p=15, . . . , 22. According to different numbers of CSI-RS ports, when there may be 1, 2, 4 and 8 antenna ports, CSI-RS configuration manners (or called multiplexing factors) which may be supported by each subframe are respectively: under a normal Cyclic Prefix (CP), 32 (20 for Frequency Division Duplexing (FDD) and 12 for Time Division Duplexing (TDD)), 16 (10 for FDD and 6 for TDD) and 8 (5 for FDD and 3 for TDD); and under an extended CP, 28 (16 for FDD and 12 for TDD), 14 (8 for FDD and 6 for TDD) and 7 (4 for FDD and 3 for TDD). Moreover, a CSI-RS sending period may be 5/10/20/40/80 subframes; and the sending period and a CSI-RS sending subframe offset are configured in a unified manner. When TM9 is configured for User Equipment (UE), one set of CSI-RS may be configured for the UE; and when TM10 is configured for the UE, one or more sets of CSI-RSs (at most 3 sets) may be configured for the UE.
A CSI-IMR is defined in TS 36.213-b30, and when TM10 is configured for UE, one or more sets (at most 3 sets) of CSI-IMRs may be configured for the UE. Wherein, a CSI-IMR is determined by two parameters, i.e., a Zero Power (ZP) CSI-RS configuration and a ZP CSI-RS subframe configuration. Wherein, a ZP CSI-RS represents a CSI-RS which may be configured to be sent under zero power.
In Non Ideal Backhaul (NIB), an IMR is required to be configured with reference to a ZP CSI-RS of a coordination cell. For example, when a coordination cell corresponding to a CSI process does not perform muting, an IMR may not be configured to a resource corresponding to a ZP CSI-RS of the coordination cell, and when the coordination cell corresponding to the CSI process performs muting, the IMR is required to be configured to the resource corresponding to the ZP CSI-RS of the coordination cell. However, ZP CSI-RS configuration of the coordination cell has a requirement on determining a final ZP CSI-RS resource with reference to configuration of the IMR, which may cause the problem of mutual reference during configuration, thereby generating a conflict.
Similarly, during configuration of Coordinated Scheduling/Coordinated Beamforming (CSCB), nodes are required to interact with one another about weight using information of coordination beams on different resources, and since a current node may be a serving cell or a coordination cell for different users of any node, there also exists the problem of mutual reference in a beam coordination process.
In an existing scheduling architecture, two manners, i.e., distributed scheduling and centralized scheduling, are mainly adopted. Under a centralized scheduling condition, each node reports information such as CSI of a local user to a central scheduler, and the central scheduler configures a scheduling result to different nodes after scheduling; however, in such a manner, a scheduling time delay of a non-COMP user may be greatly prolonged in case of existence of a time delay for interaction among the nodes, thereby causing influence on performance of the non-COMP user. Under a distributed scheduling condition, although independent scheduling among the nodes may avoid the scheduling time delay, a requirement on interaction about information such as CSI and resource mapping manners among interfaces and the problem of mutual reference of ZP CSI-RS coordination configuration and BeamForming (BF) weight and resource coordination may cause complexity in interaction among the nodes and difficulty in coordination.